Apparatus for grinding bushings



April 15, 1947' P. F. DANIELSON 2,418,871

APPARATUS FOR GRINDING BUSHINGS Filed Sept. 17, 1945 2 Sheets-Sheet 1 /2/9 Q /s F 62 9 11 /6 1 65 6/ INVENTOP. P4111. E DAN/ELSO/V- April 15,1947. DANIEYLSON 2,418,871

7 APPARATUS FOR GRINDING BUSHINGS Filed Sept. 17, 1945 2 Sheets-Sheet 2lllll ymumn V IN V ENTOR.

Patented Apr. 15, 1947 UNITED STATES PATENT OF FlCE 2,418,871 APPARATUSFOR GRINDING BUSHINGS Paul F. Danielson, Los Angeles, Calif. ApplicationSeptember 17, 1945, Serial No. 616,705

8 Claims.

. The present invention relates to grinding de vices of a characterwhich may be incorporated in grinding machines, either as an attachmentor as an integral part thereof.

When a series of bushings are to be externally ground to a givendiameter, with the external and internal curved surfaces in concentricrelationship, it is ordinary practice to fit each bushing tightly ona'tapered mandrel or other rod and to grind the bushings individually tosize. While this method produces satisfactory results, at the same timeit is slow and laborious. A good operator following this procedure willgrind 1500 bushings to size in eight hours, Whereas the same operatorutilizing the invention of this applicationwill grind the same number ofbushings in one hour.

The invention has for an object an attachment which is easily installedon any existing type of grinder equipped with sliding centers, whichrequires but slight adjustment, is positive in its operation, assuresaccurate results in the work being ground, and is superior to methods ofgrinding work to a given concentricity now known to the inventor.

Qther objects of the invention so arranged as to permit severalbushings, all of which or any of which may have irregular surfaces, tobe ground sequentially to the same outside diameter.

. In the practice of my invention I may place a number of bushings upona mandrel interposed between centers and grind the external surfacesthereof to a selected dia-meterand in such a manner that said surfacesare concentric with the bores in said bushings.

. An object of the invention is to provide a means whereby bushingscarried on a mandrel are positively rotated during a grinding operationwithout the necessity of rotating the mandrel.

Anotherrobject i to provide means whereby bushings of uneven externaldiameter may be loosely placed upon a mandrel and still be ground toanaccurate external diameter, the external include a device surface ofwhich is concentric with the bore in said bushings.

With the above and other objects in view, the invention consists in thenovel and useful provision, formation, construction, association andrelative arrangement of parts, members and features, all as shown in acertain embodiment in the accompanying drawings, described generally andmore particularly pointed out in the claims.

. In the drawings: p

Fig. 1 is a top plan view of the improved grinding attachment shownincorporated on a grinding machine; 7

Fig. 2 is a fragmentary side elevation on an enlarged scale of theimproved attachment of the invention;

Fig. 3 is a-sectional view on the line 3-3 of Fig. 2;

Fig. 4 is an end elevation of certain portions of the attachment lookingin the direction of the arrow 4 of Fig. 2; and

Figs. 5 and 6 are diagrammatic views illustrating a grinding wheel,certain members of the attachment and work interposed therebetween.

Referring now with drawings:

The present invention is directed to the grinding of objects which areloosely carried on a mandrel, the mandrel being interposed betweencenters.

The attachment as shown in Fig, 1 at I is adapted to be incorporated insocalled arbor type grinding machines. It makes no difference so far asthe attachment is concerned whether the work is fed past the grindingwheel or the grinding wheel is moved relative to the work. No par.ticular attempt will be made to describe any specific grinding machine,other than to mention that such a machine incorporates a grinding wheel2 suitably mounted on a shaft 3, the shaft being carried in'a bearingbox 4, with one end of the shaft providedwith a pulley 5. Suitable meansis provided for rotating the pulley 5, such as by a continuous belt 6passed over pulleys 5 and 1, the latter pulley being mounted on theshaft of a motor 8. The grinding machine shown likewise incorporates atable 9, movable within ways I0 of a bed I I, and said table carries aheadstock 12 and a tailstock l3, both stocks having work-holding centersI 4 and I5. As is customary in grinders, either an automatic means isprovided for moving the table relative to its bed, or a hand operatedfeed is provided, and sometimes both of such feeds. A pilot wheel forcontrolling table travel is shown at It, the function of which is tofeed the table in one of two directions at a rate of speed desired bytheoperator, At I l is shown a micrometer cross feed attachment whichregulates the degree of cut or grind to be performed on the work. As isusual, such means controls movement of the grinder wheel toward or awayfrom the work. The lever l8 locks or unlocks the tailstock, so that amandrel may be particularity to the -means 39, constituting a boltpositioned between centers l4 and 15, or removed from therebetween,

The attachment I functions to positively rotate at a selected R. P. M.work indicated generally as [9, carried on a mandrel 20, the mandrelbeing interposed between centers i l and 15. The attachment l includes ablock 21 formed with a slot, such as T-slot 22, for guiding movement ofslide 23, the said slide having itsbase portion formed to fitwithin theT-slot, as indicated at 24. This slide carries a bracket 25, having aside Wall 26, substantially normal to the top surface 21 of the slide,and a post 28 spaced from the side wall 26 and paralleling the same. Aframe designated generally as 29 is supported by the bracket 25. Thesaid frame 29 includes a part 30 having substantially parallel side wallsurfaces, which part is interposed between wall 26 and post 28, as bestshown in Fig. 3. Said part is provided with an enlarged transverse bore3|, adapted to accommodate a bolt 32 passed therethrough and held bywall 25 and post 28. Spaced from bore 3! is a bore 33, which iselongated in form and has a counterbore at 34. A bolt 35 has its head 36received within the counterbore, the opposite end of said bolt beingpassed through bore 3! in wall 26 and secured in position of service bya nut 38. It will be seen that the frame 29 may have its part 30reciprocated a slight distance between the members 25 and 28 of bracket25. This reciprocation is controlled by adjustment having threadedengagement with a threaded bore 40 in the end 'of member 35. The shankof the said bolt is passed through an enlarged opening 4| of plate 42.The head of the bolt engages the outer surface of said, plate andtnuslimits movement of the frame '29 in one directionh This plate is securedto wall--26, t 43 by means 44. Springs "45 are interposed between thesaid plate and the end 45 of member 30. Any suitable means may be usedfor holding the springs in positio'n of service, such as by formingpockets 41 in both 'thesaidplate and the end 46 for confining endportions of said springs, see Fig. 2. "Frame 29 has an enlarged-headportion 48, which is offset relative to portion 30. This con- 'structionprovides two pairs of upper and lower bearing'members' 49, 5B, 51 and52, between'pairs of which are shafts 53 and 54. Mounted on the shaftsare rollers '55 and 56. The shafts 53 and 54 havekeyed thereto gears 5'!and 58. The frame 29 rotatively carries a gear 59, the teeth of whichare in mesh with teeth of the gears 5! and 58, and a gear likewisecarried by the frame has the teeth thereof in engagement with the teethof gear 59. Gear 62 is adapted to be driven by a motor Bl. In theembodiment shown the motor shaft drives a speed reducer 62, the shaft ofwhich'reducer turns the universal coupling 63, to which is connected alink 64, which link through a universal coupling 65 is connected togear, 60.-

A plate 56 is secured to the wall 26 by means 61, the saidplateoverlapping the roller 54. The overlapped portionof the platecarries a spring loaded screw 58, the end of which screw engages theonset head. 48. The purpose of such an arrangement is to stabilize thebearing members of the. head. The block 2| is provided with a SU-PPQItv69 for a bell crank lever 10. The said support is provided with anelongated slot I l, and a bolt [2 is passed through the bell crank atits apexand through said slot H. The short, lever 13 is pinned to link14, the link in turn being 4 pinned to slide 23. The longer lever ofsaid bell crank carries a hand grip whereby the lever may be easilyrocked.

The operation, uses and advantages of the invention are as follows:

It is to be noted that roller is of greater diameter than roller 56.These rollers function in the capacity of pressure drive means for thework; specifically the larger roller provides a tangential driving forceagainst the work to turn the work at a given rotational speed, while thesmaller roller 55 functions to retard the rotation of the work or act asa means for taking up any rotational slack, all to the end that the workwill be rotated at a continuous speed, which is to say there will be nointerruptions in the rotation. It is of course obvious that both rollersare rotated at the same speed, but that the larger roller has a greatercircumference than the smaller roller, hence when the two rollerscontact the work the smaller roller tends to retard rotation of thework, the resultant rotation of the work is therefore constant andwithout interruption.

After the block 2! has been fastened to the bed of the grinding machineand so positioned that the plane of the grinding wheel 2 transverselycuts the pressure drive rollers, the driven gear is connected with themotor 6! through suitable reduction gearing 62. Thus the pressure driverollers 55 and 56 are positively driven through gears 51-563 inclusive,the pressure drive rollers revolving in the same direction, as indicatedby the arrows on said rollers in Figs. 5 and 6.

It is obvious that there must be a difierence in rotative speeds betweenthe pressure drive rollers and the grinding wheel; and it is furtherobvious that in order to perform a proper grinding operation upon thework that the work should be rotating prior to contact with the grindingwheel. For this reason the rollers 55 and 55 are of such length as toprogressively rotate the work in advance of contact of the work withsaid grinding wheel, as illustrated in Fig. 1. The arrangement is suchthat the rollers continue to rotate the work until the work has beenfreed from grinding wheel contact. Preferably the two rollers are formedof a material adapted to positively drive the work, and I may utilizefor the material of said rollers any of the well known rubberized bondedabrasives now on the market.

If the work to be ground constitute bushings, the said bushings,irrespective of uneveness of external surface, are assembled on amandrel so as to extend substantially the length of said mandrel withthe bushings substantially free to rotate thereon. The mandrel, such as2!], is then interposed between the centers l4 and I5 of the headstockand tailstock. The index dial l l is adjusted so that the periphery ofthe grinding wheel 2 is positioned to remove material from the work togive the work a selected external diameter. In the arrangement shown,the work, if it happens to be bushings, may have difierent externaldiameters or bores; however, regardless of bore diameter, the externaldiameter of all the bushings will be the same after a grinding operationand the external surface will be concentric with the bore insaidbushings.

As previously pointed out, there is a difference in diameter between thepressure driving rollers 55 and 56. Both of these rollers contact thework as indicated in Figs. 5 and 6. These rollers are brought intocontact with the work when the bell crank 15 is moved to the positionshown in Fig. 2.

When the bushings have a like internal diam- Slide 23 eter, the saidbushings will fit fairly'tightly on the mandrel, yet are capable ofrotating, as for instance illustrated in Fig. 5. If however the internaldiameter of the bushing is larger than the diameter of the mandrel, acondition similar to that shown in Fig. 6 may arise. However, differencein internal diameter of the bushing will not change the operation of theattachment, and the external surface of the bushing will be groundconcentric with the bore in said bushing with an O. D. the same as forall other bushings. This results by reason of the construction of theattachment, wherein viewing Fig. 6 it will be observed that the pressuredriving rollers contact two portions of the periphery of the work andforce'the work into eccentric relationship relative to the mandrel. Thiseccentric relationship is maintained during a grinding operation, withthe result that the inner bore and the external cylindrical surface ofthe bushin are concentric, a feature of great importance and one whichso far as the inventor is aware is not accomplished by grinding machinesnow known to him.

The pressure necessary to be exerted against the work by the rollers inorder to positively turn the same, may be determined experimentally bythe operator, whereupon the bolt 12 is tightened at a given positionwithin the slot 1 I. Preferably the lever when finally adjusted extendsslightly over center. When the bell crank is swung from the position ofFig. 2 to the left of the showing of said figure, lever 13 will assume avertical position and move the link, thus moving the slide 23, whichcauses disengagement of the rollers 55 and 56 from the work. Having oncedetermined the pivot point for the bell crank lever, the operator needpay no further attention to the adjustment for a given 0. D. of bushing,but simply feed the table 9 by turning the pilot wheel l6 so that thework is progressively moved past the grinding wheel 2. Upon completionof a grinding operation on all of the work, the operator removes themandrel with the work thereon from between the centers and places on themandrel further bushings to be ground.

If we assume that the thickness of the bushing relative to its innerbore varies at given points, then as the pressure drive rollers 55 and56 rotate the work, the frame 29 may move relative to bracket 25. Thusthe rollers at all times follow the contour of the surface of the workand move either forward or backward, due to the construction shown inFigs. 2 and 3,.wherein it is to be observed that the frame is capable ofmovement between the bracket members 26 and 28 against pressure exertedby the springs 45. These springs at all times urge the rollers towardsthe work and the extent of the forward movement of the rollers towardsthe work is regulated by bolt 39.

Various refinements of details may be incorporated in the attachment,such as for instance the guard 15 attached to the forward end of theThis guard functions to prevent the coolant from entering between theguide for the slide and the block and in any manner impeding itsoperation, and there may be provided a guard between the grinding wheeland the work, so that the coolant liquid will not contact theattachment.

The method of securing the block 2| to the bed of the lathe is notdetailed, but any suitable means may be utilized, and preferably thedevice may be bolted to the grinder bed.

Iclaim: y

1. The combination with a grinder having a driven grinding wheel adaptedto have regulated contact With work, a movable headstock and a tailstockprovided with centersbetween which centers is placed a mandrel uponwhich cy1indri-' cal objects constituting the work are positioned to beground, the said work being rotatable upon said mandrel; of a device forpositively rotating the work as the headstock'and tailstock are moved toprogressively bring the Work into grinding wheel engagement; said deviceincluding a frame, a pair of spaced apart rollers rotatably carried bysaid frame, a slide, and resilient means between said slide and saidframe for normally urging said frame in one direction; means forpositively rotating both rollers and means for moving said slide toposition the rollers in work engagement under the resilient action ofsaid first means. 2. The combination with a grinder havinga drivengrinding wheel adapted to have regulated contact with work, .a movableheadstock and a tailstock provided withcenters between which centers isplaced a mandrel upon which cylindrical objects constituting the workare positioned to be ground, the said work being rotatable upon saidmandrel; of a device for positively rotating the work as the headstockand tailstock are moved to progressively bring the work into grindingwheel engagement; said device including a frame, a pair of spaced apartrollers rot-atably carried by said frame, a slide, and resilient meansbetween said slide and said frame for normally urging said frame in onedirection; means for positively rotating both rollers and means formoving said slide to position the rollers in work engagement under theresilient action of said first means, the said last named meanscomprising an adjustably positioned lever.

3. The combination with a grinder having a driven grinding wheel adaptedto have regulated contact with work, a movable headstock and a tailstockprovided with centers between which centers is placed a mandrel uponwhich cylindrical objects constituting the work are positioned to beground, the said work being-rotatable upon said mandrel; of a device forpositively rotating the work as the headstock and tailstock are moved toprogressively bring the work into grinding wheel engagement; said deviceincluding a block for attachment to a fixed portion of the grinder andpositioned opposite to and in the plane of the said grinding wheel, aslide carried by said block and movable relative thereto, a frame andmeans for securing said frame to said slide; a pair of work engagingrollers carried by the frame and adapted to be brought into workengagement, and means for positively rotating said rollers.

4. The combination with a grinder having a driven grinding wheel adaptedto have regulated contact with work, a movable headstock and a tailstockprovided with centers between which centers is placed a mandrel uponwhich cylindrical objects constituting the work are positioned to beground, the said work being rotatable upon said mandrel; of a device forpositively rotating the work as the headstock and tailstock are moved toprogressively bring the work into grinding wheel engagement; said deviceincluding a block for attachment to a fixed portion of the grinder andpositioned opposite to and in the plane of the said grinding wheel, aslide carried by said block and movable relative thereto, a

frame and means for securing said frame tosaid slide: a pair of workengaging rollers carried by the frame and adapted to be brought intowork engagement, means for positively rotating said rollers, andresilient means for maintaining said rollers in said work engagement.

5. In a device of the character disclosed, a frame, a pair of spacedapart rollers rotatably secured to said frame, a slide provided withsubstantially parallel side walls between which a'portion of said frameis positioned, means carried by said side walls for movabl'y mountingthe frame therebetween, and resilient means for urging said frame in onedirection; means for rotating said rollers and adjustable means formoving the said slide to position said rollers in work engagement. 6. Ina device of the character disclosed, a pair of friction rollers forcontact with work, means for simultaneously turning said rollers, one ofsaid rollers being of lesser diameter than the other thereof, to therebyefiect constant rotation of the work.

'7. The combination with a grinding wheel, a mandrel upon which a numberof bushings are placed for rotation, the said mandrel adapted to be fedpast the grinding wheel to in turn grind the bushings, of a pair offriction type drive rollers for contact with the bushings; and adaptedto cause rotation of the bushings in advance of contact with thegrinding wheel and during contact therewith; one of said rollers havinga greater diameter than the other thereof; and means for rotating saidrollers at a constant speed and whereby the smaller diameter rollerretards rotation of the bushings to thereby effect anuninterrupted-rotation thereof.

8. The combination with a grinder having a driven grinding wheel adaptedto have regulated contact with work, a movable headstock and tailstockprovided with centers between which centers is placed a constantdiameter mandrel upon which a plurality of bushings constituting thework are positioned to be ground, the said bushings floating upon saidmandrel; of a pair of drive rollers for rotatin the bushings in advanceof and during contact with the grinding wheel as the headstock andtailstock are moved, one of said rollers being of lesser diameter thanthe other roller, and the roller of greater diameter functioning as themain driving roller for said bushings, and the roller of lesser diameterfunctioning to pick up any rotative slack in the bushings due to anyuneven surface on said bushings, to thereby effect a constant rotativespeed of the bushings.

PAUL F. DANIELSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,345,308 Wallace Mar. 28, 19441,845,122 Briney Feb. 16, 1932 1,874,301 Jones Aug. 30, 1932 1,878,116Deutsch Sept. 20, 1932 2,023,720 Asbridge Dec. 10, 1935 1,735,333 OlsonNov. 12, 1929

